In the early ‘60’s I was riding the rails in Western Canada, but the new version whereby one could enter an engine unit cab and sit out the ride in relative comfort. Units were much less powerful in those days and many units were required to provide sufficient power to cross the Rockies.
I hoped a unit on Canadian Pacific Railroad (CPR) in Revelstoke (a Division point where crews were exchanged) one evening, bound for Vancouver. I seldom rode the CPR units, preferring the more tender mercies of Canadian National crews.
I didn’t know that section of the CPR line passed through the Connaught Tunnel, some 5 miles long. Once we entered the tunnel I soon encountered difficulty breathing since I was in the last of seven units and the exhaust of units in front of me was entering the cab. I soon lost consciousness.
Some time later I regained consciousness while the train negotiated a bridge crossing the nearby Kicking Horse River. The only observable effect was a spitting headache but I’ve always wondered if I sustained some brain damage from oxygen deprivation. 🙂